The oxidation of cyclohexane is a process of very great commercial importance. The major important oxidation products, cyclohexanol and cyclohexanone, are useful in the production of many high volume chemicals of commerce. For example, such important chemicals as adipic acid, caprotactam, phenol and others are produced from the above oxidation products.
In high volume, efficient processes, it is advantageous that the reaction be carried out in a continuous fashion in a series of separate reaction zones. The reaction selectivities which are achieved by known oxidation procedures, and the methods and equipment employed have not always proved completely satisfactory. For example, the art such as represented by British Pat. No. 1,025,752, has suggested a reaction system whereby vapor from the final reaction mixture is passed in countercurrent flow to the liquid oxidation reaction mixture in the series of reaction zones. Such a procedure has certain disadvantages which include, for example, necessary pressure differentials at various points in the system as well as the enlarged equipment necessary at each point to handle the high vapor flows.
The procedures which have been used in the prior art have not been entirely satisfactory and there has remained considerable room for significant improvements.